The Washington Nationals recalled right-handed pitcher Nathan Karns from Harrisburg of the Double-A Eastern League and optioned left-handed pitcher Xavier Cedeno to Syracuse.

Karns is scheduled to make his Major League debut tonight when Washington hosts Baltimore at Nationals Park. The 25-year-old went 4-2 with a 4.60 ERA in nine starts this season with Harrisburg, posting 11.0 strikeouts per 9 innings (55 K/45.0 IP) and a 3.1/1 strikeout-to-walk ratio (55 K/18 BB). Karns held his opponents to fewer than two earned runs in five of his nine starts, including a 7.0-inning, 13-strikeout winning effort on April 20 vs. Altoona.

The Nationals Minor League Pitcher of the Year in 2012, Karns is 18-8 with two saves and a 2.70 ERA in 46 games/40 starts during his three seasons ('11-13) of professional ball. He led Washington farmhands last season with a 2.17 ERA and 148 strikeouts pitching for the Nationals' Single-A affiliates in Hagerstown (South Atlantic League) and Potomac (Carolina League).

Karns, who will wear No. 57, was selected by the Nationals in the 12th round of the 2009 draft out of Texas Tech University.

Cedeno did not appear in any games during his one-day stint with the Nationals.